Size S12 footprint and 230 A rating
The 3RW4073-2BB35 is a Siemens SIRIUS soft starter in the Size S12 frame — 160 mm wide, 230 mm tall, 278 mm deep. That footprint is the first thing to check against your panel layout; the S12 is the largest standard frame in the 3RW40 family and needs the matching gland plate and busbar clearance. If your motor FLA lands near the 230 A mark and the panel ambient runs above 40 °C, the 50 °C derating figure is the one to size against — don't spec by the 40 °C number alone. Built around thyristor technology with adjustable current limitation and integrated motor overload protection.
Wiring and termination — what fits
Main circuit connection is via busbar, accepting stranded cable from 70 to 240 mm² and finely stranded from 50 to 240 mm². The back clamping point takes 250–500 kcmil; the front clamping point takes 3/0–600 kcmil. If you're landing parallel runs, the terminal allows two conductors per phase — min 2x 2/0, max 2x 500 kcmil. That's a standard spring-cage range — no special ferrules needed, but stranded wire with a ferrule seats cleaner.
Environmental limits and protection class
The derating temperature threshold kicks in at 40 °C — the 230 A rating holds up to that point, then drops linearly as shown in the derating curve. Maximum motor cable length is 300 m — factor that into the install if the motor is remote from the panel. The minimum load is 20% of the soft starter's rated current, so it won't regulate properly on a grossly undersized motor.
Active production — sourcing posture
No official successor or cross-reference is listed — the 3RW4073-2BB35 is the current production variant in the SIRIUS line.